﻿412 
  J. 
  W. 
  JENKINSON. 
  

  

  The 
  first 
  part 
  of 
  this 
  criticism 
  has 
  already 
  been 
  met 
  by 
  

   Boveri 
  (1901), 
  and 
  I 
  can 
  do 
  no 
  better 
  tlian 
  fully 
  endorse 
  his 
  

   reply. 
  While 
  admitting- 
  fully 
  that 
  many 
  particles 
  besides 
  

   the 
  ceutrosomes 
  will 
  stain 
  in 
  this 
  way, 
  and 
  that 
  many 
  bodies 
  

   which 
  have 
  been 
  described 
  as 
  centrosomes, 
  even 
  at 
  the 
  poles 
  

   of 
  the 
  spindle, 
  may 
  be 
  the 
  artificial 
  products 
  of 
  " 
  concen- 
  

   trische 
  Entfjirbung," 
  he 
  justly 
  points 
  out 
  that 
  two 
  such 
  

   bodies 
  lying 
  in 
  a 
  sphere, 
  or 
  one 
  lying 
  excentrically, 
  cannot 
  

   be 
  thus 
  accounted 
  for. 
  Moreover 
  the 
  centrosome, 
  if 
  not 
  

   actually 
  visible 
  intra 
  vitam, 
  may 
  often 
  be 
  seen 
  in 
  an 
  un- 
  

   stained 
  preparation. 
  

  

  The 
  second 
  part 
  contains 
  what 
  I 
  believe 
  is 
  a 
  valuable 
  con- 
  

   tribution 
  to 
  the 
  theory 
  of 
  the 
  origin 
  of 
  both 
  centrosome 
  aud 
  

   aster, 
  of 
  the 
  former 
  through 
  precipitation 
  by 
  nucleic 
  acid, 
  of 
  

   the 
  latter 
  by 
  a 
  process 
  of 
  ''Selbststrahhmg" 
  about 
  the 
  centro- 
  

   some 
  so 
  produced. 
  The 
  conclusion 
  drawn 
  is, 
  however, 
  wholly 
  

   unwarrantable, 
  and 
  would 
  never 
  have 
  been 
  adopted 
  if, 
  as 
  

   Boveri 
  points 
  out, 
  Fischer 
  had 
  kept 
  the 
  hard 
  facts 
  of 
  

   cytology 
  in 
  sight, 
  instead 
  of 
  deliberately 
  ignoring- 
  the 
  gradual 
  

   cycle 
  of 
  changes 
  which 
  these 
  cell 
  organs 
  undoubtedly 
  pass 
  

   throug'h. 
  

  

  II. 
  Descriptive. 
  

  

  A. 
  Maturation. 
  

  

  1. 
  First 
  polar 
  division. 
  

  

  (a) 
  Metaphase. 
  — 
  In 
  my 
  earliest 
  stage 
  the 
  spindle 
  is 
  fully 
  

   formed, 
  and 
  is 
  at 
  the 
  surface 
  (fig. 
  1) 
  ; 
  its 
  direction 
  is 
  either 
  

   radial 
  or 
  slightly 
  oblique. 
  The 
  spindle 
  is 
  closely 
  surrounded 
  

   by 
  yolk-granules 
  and 
  pigment, 
  and 
  consists 
  of 
  wavy, 
  

   frequently 
  anastomosing 
  fibrillge. 
  The 
  appearance 
  is 
  not 
  

   inconsistent 
  with 
  the 
  view 
  that 
  we 
  have 
  here 
  to 
  do 
  with 
  

   elongated 
  alveoli. 
  Some 
  of 
  the 
  spindle-fibres 
  are 
  united 
  in 
  

   definite 
  bundles, 
  and 
  to 
  some 
  of 
  these 
  bundles 
  the 
  chromo- 
  

   somes 
  are 
  attached. 
  Almost 
  all 
  the 
  fibres 
  pass 
  continuously 
  

   from 
  one 
  pole 
  to 
  the 
  other, 
  but 
  at 
  the 
  outer 
  end 
  of 
  the 
  spindle 
  

  

  